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Category: Articles
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Ground Loops
Updated with new material 7th January 2019 This set of c. 70 slides is the culmination of my experience over a period of about 25 years building power amplifiers and preamplifiers. I first started out in audio around 1975 or 76 as a teenager. Some of my creations were reasonably quiet – through pure luck…
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MC Head Amp Circuit Compendium
Here is the new updated moving coil head amp designs compendium – updated 31 July 2019. The first file is a PDF compendium of about 28 different circuits with noise, distortion and current consumption details. All the LTspice sim files are zipped in the second file. What is immediately apparent from this is that having…
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Hifisonix Ripple Eater PSU for the sx and kx-Amplifiers
The PCB’s are through hole plated and silk screened and are available from Jim’s Audio here: Ripple Eater PSU for kx and sx Amplifiers (please note these PCB’s are not available from the Hifisonix Shop) Here is an Excel file with the BOM: Ripple Eater PSU BOM The BOM is provided for assistance – always…
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How to wire-up a Dual Mono Bloc Amplifier
A few people have asked about wiring up a dual mono amp aka dual mono bloc. In a dual mono bloc there are separate power supplies and lots of opportunity for cross channel ground loops and ordinary ‘classic’ ground loops as well. This wiring scheme addresses the situation were unbalanced connections between the source equipment…
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Noise in Electronic Circuits
I’ve gathered a few articles here on noise as a go-to reference for anyone interested in the subject. These articles really focus on Johnson noise and not induced noise which is discussed in depth in the ‘Ground Loops’ post elsewhere on this site. I will update this post with new material as and when it…
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Technical Requirements of Phono Preamplifiers by Tomlinson Holman
The two articles below were written in the 1970’s, nearly a decade before the arrival of the CD and the ‘perfect sound forever’ claim made by Philips. There was a lot of focus on phono amplifier performance at the time which it could be argued was triggered by the arrival of very high performance turntables…
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Richard Lee’s Ultra-Low Noise MC Head Amp
This design was a development of Marshall Leach’s MC head-amp, from the 1970s, and to my knowledge, Richard Lee’s implementation presented here has not been bested in terms of noise – about 280pV/rt Hz in a well-implemented exemplar – other than in the Hifisonix X-Altra MC/MM Phono Preamplifier. Importantly, it requires only about 12mA current…
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My Loudspeakers
I bought a pair of B&W 703’s in about 2003 and they travelled with me all around Asia when I worked there as an expat for ten years. These are big loudspeakers with fantastic bass and mid-range articulation. The treble may be a little forward for some, but for Jazz, big band and rock they…